sorry if this already exists but i felt people might want to know each others strategies for bosses or just playing in general.
to start; I either like to get magneto or doom, use there shield special and bombard enemies with ranged, or get hulk,thing or collosus and use their "bull-rush" ability
I like using characters with tk wherever I can just throw enemies from places, like after aeronautics in the Skrull world or on my way to Raven Spyre.
For Bosses, using characters that can become invisible (Nightcrawler, Nick Fury, Sue, Black Panther and Cap Marvel) makes it ridiculously easy. If you know how to control Black Widow's Controlled Burst or use fantastic fists on Mister Fantastic it's really easy too.
I have tried figuring out which characters can fight FF and Dr. Doom completely alone. Those that did it are: Thor, Silver Surfer, Doc Strange, Magneto, Storm, Iceman, Human Torch and all those that become invisible.